1. Field of the Invention
The present invention relates to a high-frequency thawing apparatus and a thawing method for executing thawing processing by applying high-frequency waves to a frozen material, such as meat and fish and seafood done with freezing processing.
2. Description of the Related Art
A high-frequency thawing apparatus that executes thawing processing by applying high-frequency waves to a frozen material, such as the one described in Patent Document 1, has been known. This high-frequency thawing apparatus is configured to supply a frozen material with high-frequency power from a high-frequency oscillator via a pair of opposing electrodes while the frozen material is sandwiched between the opposing electrodes, so that the frozen material sandwiched between the opposing electrodes is thawed by dielectric heating that takes place upon supply of high-frequency power.
Incidentally, the high-frequency thawing apparatus described in Patent Document 1 adopts a configuration to generate a uniform electric field within a material to be heated by covering a frozen material with a pair of opposing electrodes in a reliable manner. In a case of such opposing electrodes, however, energy of high frequency waves tends to concentrate on the boundary of a medium, that is, the crest edge portion of the frozen material, and this portion is heated more readily than the other portions, which poses a problem that the frozen material is not thawed uniformly.
In particular, in a case where the frozen material is meat, because the frozen material is heated by means of dielectric heating produced by high-frequency waves combined with a Joule heat on top of that the dielectric loss and the electric conductivity of fat contained in the meat are high, when the fat falls on the crest edge portion of the frozen meat, the crest edge portion of the thawed meat comes to a boil. This causes an inconvenience that the commercial value is declined.
Patent Document 1: Japanese Unexamined Patent Publication No. HEI EI 8-266257.